A new species of Gompholobium (Fabaceae: Mirbelieae) from the Pilbara bioregion of Western Australia

2012·2.2 MB·English

by  Wilkins, C F

C.F. Wilkins & M.E. Trudgen, A new species of Gompholobium 31
Nuytsia
The journal of the Western Australian Herbarium
22(1): 31–40 Published online 23 March 2012
A new species of Gompholobium (Fabaceae: Mirbelieae) from the
Pilbara bioregion of Western Australia
Carolyn F. Wilkins and Malcolm E. Trudgen
Western Australian Herbarium, Department of Environment and Conservation,
Locked Bag 104, Bentley Delivery Centre, Western Australia 6983
Abstract
Wilkins, C.F. & Trudgen, M.E. A new species of Gompholobium (Fabaceae: Mirbelieae) from the
Pilbara bioregion of Western Australia. Nuytsia 22(1): 31–40 (2012). Gompholobium oreophilum
C.F.Wilkins & Trudgen, a new species from the Pilbara bioregion of Western Australia, is described
and compared to its close relatives G. karijini Chappill and G. polyzygum F.Muell. The different
habitat preferences and the possible hybridisation between G. oreophilum and G. karijini, which is
also endemic to the Pilbara, are discussed. A key and distribution maps are provided.
Introduction
Gompholobium Sm. is an Australasian genus of 44 species in tribe Mirbelieae of the Fabaceae (Chappill
et al. 2008). It is found in all Australian States and mainland Territories and extends outside Australia
to Wetar Island in the Lesser Sunda Islands, and New Guinea. While it is species-rich in the south-
west of Western Australia, Gompholobium is less diverse in the more arid parts of the State, and the
new species described herein increases the known diversity of the genus in the Pilbara bioregion from
one species to two.
Gompholobium was first described by Smith (1798) who gave the distinguishing features of the genus
as a ventricose fruit with numerous seeds, ternate or imparipinnate leaves and large, yellow flowers.
Recently, in a revision of Gompholobium, Chappill et al. (2008) gave modified distinguishing features,
including the separation of the calyx lobes nearly to the hypanthium, a feature shared in the tribe
with Jacksonia R.Br. ex Sm., Leptosema Benth. and Latrobea Meisn., and the inflated globose or
ellipsoid fruit, a feature shared with Sphaerolobium Sm. In addition, Chappill et al. (2008) indicated
that seeds of all observed Gompholobium species have much longer (> 2 mm) funicles than those of
other observed legume genera, a feature also noted by Cameron (1988) in a study of the embryology
of Australian legume genera.
Chappill et al. (2008) also described a new species, G. karijini Chappill, to separate material from the
Hamersley Range from the somewhat similar G. polyzygum F.Muell., which occurs to the east and
south of the Pilbara bioregion. Chappill noted that the new species was variable; the type specimen is
almost glabrous, while the remainder of the collections included by Chappill in G. karijini are villous.
© Department of Environment and Conservation 2012 ISSN 2200-2790 (Online)
http://florabase.dec.wa.gov.au/nuytsia/ ISSN 0085-4417 (Print)
32 Nuytsia Vol. 22 (1) (2012)
This paper describes the villous entity as a new species, G. oreophilum C.F.Wilkins & Trudgen, and
compares it to its closest relatives, G. polyzygum and G. karijini.
Methods
This study is based on examination of fresh material, and herbarium specimens housed at PERTH.
Habitat and lithology information was derived from Griffin and Trudgen (2009) supplemented by a
small amount of targeted field work.
Taxonomic treatment
Species in the G. polyzygum complex have imparipinnate leaves with 4–21 leaflet pairs, leaflets with
flat margins and flowers with yellow to yellow-orange petals.
Key to species of the Gompholobium polyzygum complex
1. Plants glabrous or very sparsely hairy, with calyces glabrous except for lobe margins ..............G. karijini
1: Plants ± densely hairy, especially on branchlets and calyces
2. Leaves mostly with > 10 pairs of overlapping leaflets; leaflets mostly < 4 mm long.
Hairs on peduncles, pedicels and buds > 1 mm long (NT & WA, E & SE of
Pilbara bioregion) ................................................................................................................G. polyzygum
2: Leaves mostly with 5–10 pairs of slightly or non overlapping leaflets; leaflets
mostly > 4 mm long. Hairs on peduncles, pedicels and buds c. 0.8 mm long
(Pilbara bioregion) ..............................................................................................................G. oreophilum
Gompholobium karijini Chappill, Austral. Syst. Bot. 21(2): 122 (2008). Type: Hamersley Gorge,
Karijini National Park, Western Australia, [precise locality withheld for conservation reasons] 2
September 1991, M.E. Trudgen & S.M. Maley 10580 (holo: PERTH 06090508!; iso: AD!, CANB!,
K!, MEL 2348044!, NSW!).
Erect shrub 0.4–0.7 × 0.6–1.3 m, not viscid. Branchlets straight, glabrous or with occasional, spreading,
straight hairs c. 0.8 mm long; ribs absent. Stipules subulate, erect or scarcely recurved, 1.5–3 × 0.2–0.3
mm, glabrous except for apical tuft of hairs. Leaves imparipinnate with (4)5–10 pairs of opposite or
sub-opposite leaflets, glabrous or with a sparse indumentum of spreading hairs c. 0.8 mm long on the
rachis and leaflets; petiole 0.6–2.1 mm long; petiolules 0.5–0.6 mm long. Leaflets all similar, elliptic or
obovate, (3.1–)4–6.5(–8.5) × (1.2–)2.5–5 mm, not tuberculate, discolorous, olive green or grey-green,
not glaucous; bases attenuate; margins entire and flat; apices sub-acute or obtuse, rarely acute and
straight. Flowers 4–100+ in simple or compound racemes (4–)15–20 cm long at apex of branchlets.
Peduncles 3.5–20 mm long, glabrous or with occasional, spreading, straight hairs to 1 mm long.
Pedicels 5–8 mm long, glabrous or with occasional, spreading, straight or wavy hairs c. 1 mm long.
Bracts early-caducous, subulate, 3–5 × 0.3–0.5 mm, glabrous (or rarely with occasional hairs) with tuft
of white hairs at apex. Bracteoles early-caducous, inserted on upper third of pedicel, subulate, 3.5–4
× 0.2–0.3 mm, glabrous except for a tuft of white hairs at apex. Buds ellipsoid, 6.5–7.3 × 3.5–4 mm,
red-brown or dark green, glabrous except for short hairs to 0.15 mm long on calyx lobe margins, with
tips of calyx lobes fused; apiculum absent or straight, 0.1–0.2 mm long. Hypanthium 1.2–1.5 mm long.
Calyx with adaxial lobes fused at base for 1.5–2 mm, symmetrical, 5.3–6.6 × 2–2.5 mm, the abaxial
lobes fused at base for 1.4–1.8 mm, symmetrical, 5.3–6.6 × 1.7–2.5 mm. Standard with a claw 1.5–2
× 0.9–1 mm and a broadly ovate lamina 10–11 × 12–12.2 mm, without auricles, yellow to yellow-
C.F. Wilkins & M.E. Trudgen, A new species of Gompholobium 33
orange on both surfaces, with creamish green eye markings, emarginate with indentation 0.8–1.3 mm
deep; wings straight, narrowly obovate, yellow to orange, 10–11 × 2.8–3.6 mm including claw, the
apex obtuse; keel creamish yellow, 9.5–12 × 4.3–5.8 mm including claw, the apex straight and obtuse.
Stamens with green or red filaments 8.5–9.7 × 0.3–0.5 mm; anthers sub-basifixed, narrowly ovoid,
uniform in size, 1.3–1.4 × 0.5–0.6 mm, white with a narrow, red connective. Gynoecium with a stipe
0.3–0.8 mm long; ovary 4.3–4.5 × 1.5–1.8 mm, glabrous; style c. 9.5 × 0.7 mm long, glabrous or rarely
with a dense indumentum of spreading hairs to 0.6 mm long; ovules 2, the funicles c. 1.3 mm long.
Fruit (immature) ellipsoid, glabrous, c. 7 × 7 mm. Seed only seen immature. (Figure 1)
Flowering period. January, and August to September.
Selected specimens examined. WESTERN AUSTRALIA: Wittenoom area, 5 Aug. 1971, A.M. Ashby
4172 (PERTH); Wittenoom district, Jan. 1972, L. McGuire s.n. (PERTH); plateau above Wittenoom
Gorge, Karijini National Park, 18 Aug. 1963, J.S. Beard 2884 (PERTH); Rio Tinto Gorge, NW of
Wittenoom, 2 Sep. 2011, M.E. Trudgen & E.A. Griffin MET 23685 (BRI, DNA, PERTH); Hamersley
Gorge, Karijini National Park, 24 Sep. 2006, N.G. Walsh, D. Halford & D. Mallinson NGW6538
(PERTH).
Distribution. Gompholobium karijini is confined to the Karijini National Park in the Pilbara bioregion
of north-western Western Australia, near Hamersley Gorge and Wittenoom Gorge. Further collections
of this form have indeterminate localities (Figure 2).
Habitat. Gompholobium karijini occurs in open Triodia hummock grassland with scattered shrubs
and trees on ironstone gravel. In addition to the material cited in this paper, one of us (MET) has seen
twenty-five sterile collections of G. karijini collected from an area west of Karijini National Park. Of
these collections, seventeen were collected from sites on Robe Pisolite and the others were mostly
from colluvium and alluvium types that appear to overly Robe Pisolite in valley floors (Griffin &
Trudgen 2009; limitations in geological maps mean that a few specimens could not be confidently
assigned to a geological type). The type specimen of G. karijini is also from a similar rock type to
Figure 1. Gompholobium karijini. A – habit; B – flowers. Photographs by M.E. Trudgen from M.E. Trudgen MET 23684.
34 Nuytsia Vol. 22 (1) (2012)
Figure 2. Distribution of Gompholobium karijini ( )and G. oreophilum (○).
Robe Pisolite, as it was from a cemented colluvium. Gompholobium karijini occurs on the younger
geological types in the region.
Conservation status. Gompholobium karijini is listed as Priority Two under Department of Environment
and Conservation (DEC) Conservation Codes for Western Australia Flora (Smith 2010) as it is only
known from a few populations, some of which are not thought to be under immediate threat.
Notes. Gompholobium karijini differs from G. polyzygum and G. oreophilum most obviously in being
a nearly glabrous plant. The outer surface of the calyx is glabrous except for the margins of the lobes,
rather than being densely villous throughout. For details of further differences, see under G. polyzygum
and G. oreophilum.
The protologue for G. karijini (Chappill et al. 2008) is no longer correct as it includes features of the
densely villous form that is the new species G. oreophilum. The illustration presented as G. karijini
in Figure 35 of that paper is of G. oreophilum.
A number of possible hybrids with G. oreophilum are known (see under that species for a discussion
of these).
C.F. Wilkins & M.E. Trudgen, A new species of Gompholobium 35
Gompholobium oreophilum C.F.Wilkins & Trudgen, sp. nov.
Typus: Mount Sheila, Hamersley Range, Western Australia [precise locality withheld for conservation
reasons], 2 September 2011, M.E. Trudgen & E.A. Griffin MET 23684 (holo: PERTH 07862725; iso:
CANB, K, MEL).
Gompholobium sp. Pilbara (N.F. Norris 908), Western Australian Herbarium, in FloraBase, http://
florabase.dec.wa.gov.au [accessed 7 November 2011].
Erect shrub 0.4–0.6 × 0.6–1 m, not viscid. Branchlets straight, with a dense indumentum of spreading,
straight hairs 0.4–0.8(–1.2) mm long; ribs faint or absent. Stipules subulate, erect or scarcely recurved,
1.5–3 × 0.2–0.3 mm, densely hairy. Leaves imparipinnate with (4–)9–10(–12) pairs of opposite or
sub-opposite leaflets, with a sparse to moderately dense indumentum of spreading, straight hairs
0.4–0.8 mm long on rachis and leaflets; petiole 1.5–2.6 mm long; petiolules 0.35–0.6 mm long. Leaflets
elliptic, rarely narrowly ovate or elliptic-obovate (the terminal leaflet elliptic to obovate or rarely
narrowly ovate), 4–8 × 2–5 mm, discolorous, mid green to grey-green, not glaucous; bases attenuate,
margins entire and flat; apices acute to sub-acute and straight. Flowers (5–)13–30 in racemes at apex
of branchlets, 3.8–15 cm long. Peduncles 2–6.6 mm long, with a dense indumentum of spreading,
straight hairs to 0.8 mm long. Pedicels 5–9 mm long, with a sparse or dense indumentum of spreading,
straight or wavy hairs to 0.8 mm long. Bracts late-caducous, subulate, 4–5 × 0.2–0.4 mm, with a dense
indumentum of spreading, straight or wavy hairs c. 0.5 mm long on entire abaxial surface. Bracteoles
late-caducous, inserted on upper third of pedicel, subulate, 3.5–6 × 0.2–0.3 mm, densely hairy. Buds
ellipsoid, 6.5–8.5 × 3.5–4.3 mm, red-brown, with a dense indumentum of spreading, straight hairs to
0.7 mm long, with tips of calyx lobes fused; apiculum absent or straight, c. 0.1 mm long. Hypanthium
1.5–1.6 mm long. Calyx with adaxial lobes fused at base for 1.3–1.8 mm, asymmetrical, with one
straight edge, 5.7–6 × 2–2.6 mm, the abaxial lobes fused at base for 1.3–1.4 mm, symmetrical, 5.3–5.7
× 1.8–2.5 mm. Standard with a claw 1.7–2.4 × 0.9–1.3 mm and a broadly ovate lamina 10.2–12 ×
12–16.5 mm, without auricles, yellow to yellow-orange on both surfaces, with cream eye markings,
emarginate with indentation 1.2–1.7 mm deep; wings straight, narrowly obovate, 10.3–12 × 2.5–4.3
mm including claw, yellow to yellow-orange, the apex obtuse; keel 10–12 × 4.5–6 mm including claw,
creamish yellow, the apex straight and obtuse. Stamens with pale yellow or red filaments 6.3–9.5 ×
0.2–0.5 mm; anthers sub-basifixed, narrowly ovoid, uniform in size, 1.3–1.5 × 0.5–0.6 mm, cream-
white with a narrow, grey connective. Gynoecium with a stipe 0.4–0.7 mm long; ovary 4–4.5 × 1.5
mm, with a dense indumentum throughout of spreading, straight hairs c. 0.6 mm long; style 6–6.7
× 0.3–0.7 mm, with scattered, spreading, straight hairs c. 0.3 mm long on basal third; ovules 2, the
funicles c. 1.3 mm long. Fruit ellipsoid, 6–6.2 × 6–7 mm, with mid-dense, white hairs throughout. Seeds
ellipsoid, 2.6–2.8 × 2.8 mm, without cuticular wrinkles, tan-brown with black spots. (Figures 3, 4)
Flowering period. July to September.
Selected specimens examined. WESTERN AUSTRALIA: Old Mt Bruce to Marandoo Road, WNW of
Mount Bruce, 11 Oct. 1994, B. Bromilow 25 (PERTH); above Dales Gorge, 8 Aug. 1974, G.W. Carr &
A.C. Beauglehole C4821 (K, PERTH); Site 138, Munjina E gorge lookout, 31 May 1999, G. Cassis H85
(PERTH); W of Newman, 1 Nov. 1999, J.A. Chappill & C.F. Wilkins 6331 (PERTH); Yandicoogina,
9 Sep. 1980, K.J. Gibbons 46 (PERTH); NNE of Mount Windell, ESE of Karijini National Park
headquarters, 27 July 1991, S. van Leeuwen 817 (CANB, PERTH); SE of The Governor, S of Mount
Robinson, NNE of Padtherung Hill, 18 Sep. 1991, S. van Leeuwen 1043 (PERTH); Caliwingina Creek,
N of Tom Price, 9 Sep. 1996, A.A. Mitchell PRP 1507 (PERTH); SW of Mount Bruce, 10 Oct. 1977,
M.E. Trudgen 1861 (CANB, K, PERTH); N of Munjina Roadhouse, between Newman and Karratha,
36 Nuytsia Vol. 22 (1) (2012)
Figure 3. Gompholobium oreophilum. A – habit; B – leaf detail
(A.A. Mitchell PRP 1507, drawn by L. Cobb). Scale bars = 10 mm
(A), 2.5 mm (B).
Figure 4. Gompholobium oreophilum A – habit;
B – flowers. Photographs by M.E. Trudgen from M.E.
Trudgen MET 23706.
C.F. Wilkins & M.E. Trudgen, A new species of Gompholobium 37
M.E. Trudgen &, E.A. Griffin 23683, 1 Sep. 2011 (PERTH); E of Joffre Falls, 9 Aug. 1974, J.H. Willis
s.n. (MEL); track to Eric’s Point, Karijini National Park, 17 Sep. 2006, C. Wilkins, S. van Leeuwen,
D. Halford & D. Mallinson 2214 (CANB, PERTH); Mount Bruce Road from Yampire Gorge Road,
Karijini National Park, 12 Sep. 1991, Peter G. Wilson & R. Rowe 1040 (CANB, NSW, PERTH).
Distribution. Gompholobium oreophilum is confined to the north-west of Western Australia in the
Pilbara bioregion, mainly in the Hamersley Range in an area centred on and extending to the east and
west of Karijini National Park. There are also a few records from the Chichester Range (Figure 2).
Habitat. Gompholobium oreophilum occurs in open woodland, with scattered shrubs and Triodia
hummock grassland, in red clay on ironstone gravel, often close to banded ironstone outcrops.
Collections of G. oreophilum are largely from hillslopes in erosional positions. For example, the type
specimen for G. oreophilum was collected from just below the crest of Mount Sheila, although the
species also grows on the lower slopes of this large mountain. This is in contrast to the habitat of the
majority of G. karijini populations, which grow in Robe Pisolite or colluvium and alluvium soil types
over Robe Pisolite in valley floors (Griffin & Trudgen 2009).
It is fairly clear that the two Gompholobium species in the Pilbara bioregion are largely spatially
separated by preference for different geological and habitat types.
Conservation status. Gompholobium oreophilum is widespread and not threatened at this time.
Etymology. From the Greek oreos = mountain and philos = loving, as the new species occurs on or
near mountain ranges.
Notes. Gompholobium oreophilum differs from G. karijini in having lateral leaflets that are elliptic or
rarely narrowly ovate rather than obovate, with the apex acute to sub-acute rather than obtuse. The
outer surface of the calyx is densely hairy rather than glabrous, and the inner surface of the calyx has
long, villous hairs towards the margin of the lobes rather than short, crisped hairs. The leaves have
a medium density of hairs on the rachis and leaflets rather than no, or occasional, hairs. Bracts and
bracteoles are late-caducous or persistent and villous-hairy, rather than early-caducous and either
glabrous apart from an apical tuft, or only sparsely hairy throughout.
Specimens from the Chichester Range are somewhat less hairy than those from the Hamersley
Range.
Five PERTH specimens (M.E. Trudgen 394, M.E. Trudgen 23682, R. Butler 13, A.C. Beauglehole
11472 and M.E. Ballingall 1844), that have hairs on the outer surface of the calyx, are possibly hybrids
between G. karijini and G. oreophilum. They have leaflets that are intermediate in shape between these
two species (Figure 5) and are less hairy than those of G. oreophilum. While the putative hybrids do
have densely hairy stems like G. oreophilum, the hairs on the stems and leaflets are shorter than on
typical material of this species.
Gompholobium polyzygum F.Muell., Fragm. 3: 29 (1862). Burtonia polyzyga (F.Muell.) Benth., Fl.
Austral. 2: 51 (1864). Type: ‘Inter montem Morphett et flumen Bonney’ [between Mount Morphett
and Bonney River], Northern Territory, J.M. Stuart s.n. (holo: MEL 624364; iso: K).
38 Nuytsia Vol. 22 (1) (2012)
Burtonia polyzyga (F.Muell.) Benth. var. multijuga F.Muell. ex Ewart, Proc. Roy. Soc. Victoria 19:
36 (Feb. 1907). Type: ‘Burtonia multijuga F.Muell. Forrest’s Expedition, 13 July 1874’ [location
unknown, probably from Forrest’s 3rd expedition in 1874, between Geraldton, Western Australia, and
Peake Telegraph Station, South Australia] (holo: MEL 624684, image!).
Burtonia multijuga Ewart, Proc. Roy. Soc. Victoria 19: 36 (Feb. 1907), nom. inval., given in synonymy
under Burtonia polyzyga var. multijuga.
Erect or prostrate shrub 0.3–1.5 × 0.3–0.6 m, not viscid. Branchlets straight, with a dense indumentum
of spreading, straight or curly hairs c. 1.1 mm long; ribs absent. Stipules subulate, recurved, sometimes
erect, 1.3–3.5 × 0.15–0.3 mm, densely hairy. Leaves imparipinnate with (6–)16–21 pairs of opposite,
overlapping leaflets; petiole 1.3–4 mm long, with scattered, spreading, straight or curly hairs c. 0.4 mm
long on rachis and leaflets; petiolules 0.3–0.4 mm long. Leaflets all similar, elliptic, broad-elliptic,
broad-obovate or sub-rotund, (1.5–)2–3.5(–5) × 1.6–3.3 mm, not tuberculate, concolorous, grey-green,
not glaucous; bases attenuate; margins entire and flat; apices obtuse to rounded and straight. Flowers
5–16 in racemes at apex of branchlets; subtending leaves not longer than inflorescence. Peduncle
6–14 mm long with a dense indumentum of spreading, wavy hairs c. 1.3 mm long. Pedicels 4–10 mm
long with an indumentum as for the peduncle. Bracts subulate, 3.5–10 × 0.4–0.8 mm, with a dense
indumentum of spreading, wavy hairs c. 1.2 mm long on entire abaxial surface. Bracteoles persistent,
inserted on upper third of pedicel, subulate, 3.1–9.5 × 0.25–0.5 mm, with a dense indumentum of
spreading, wavy hairs c. 1 mm long on entire abaxial surface. Buds ellipsoid, reddish brown, 7.5–8.1
× 3.5–4.2 mm, with a dense indumentum of spreading, wavy hairs c. 1.5 mm long, the tips of the
calyx lobes fused; apiculum absent. Hypanthium 1–1.4 mm long. Calyx with adaxial lobes fused at
base for 1.5–2.3 mm, slightly asymmetrical, 5.1–7 × 2.1–2.5 mm, the abaxial lobes fused at base for
0.8–1.8 mm, symmetrical, 5.3–6.5 × 1.7–2.1 mm. Standard with a claw 1.3–2.8 × 1.1–1.3 mm and
lamina 9.5–11.8 × 11–14 mm, without auricles, yellow-orange to orange on both surfaces, without eye
markings, emarginate with indentation 0.4–2.5 mm deep; wings straight, basal lobe on upper margin
Figure 5. Leaves. L, upper surface, R, lower surface. A – Gompholobium karijini, (M.E. Trudgen MET 23684); B – G. karijini
× oreophilum (M.E. Trudgen MET 23682); C – G. oreophilum (M.E. Trudgen MET 23706). Scale bar = 2 cm.
C.F. Wilkins & M.E. Trudgen, A new species of Gompholobium 39
present or absent, orange-yellow to orange, 10–12 × 3.5–4.3 mm including claw, the apices obtuse;
keel orange or yellow-green, 10–12 × 4–5 mm including claw, the apex straight, obtuse. Stamens with
pale green filaments 7.6–11 × 0.2–0.6 mm; anthers sub-basifixed, narrowly ovoid, uniform in size,
0.8–1.8 × 0.3–0.9 mm, cream with a narrow, red connective. Gynoecium with a stipe 0.5–0.8 mm
long; ovary 3.1–4.3 × 1.3–1.5 mm, with a dense indumentum of spreading, straight hairs c. 1.3 mm
long; style 5.5–7.8 × 0.25–0.3 mm, with scattered, spreading, straight hairs c. 0.3 mm long on basal
two-thirds; ovules 2, the funicles 1.3–2.2 mm long. Fruit 5.5–7 × 6.5–7.8 mm, with a dense indumentum
of spreading, straight hairs c. 1.5 mm long throughout. Seeds ellipsoid, 2.5–2.9 × 1.9–2.3 mm, without
cuticular wrinkles, yellow-brown or tan, with dark red or black markings.
Flowering period. April to November.
Selected specimens examined. NORTHERN TERRITORY: near Ulambaura Spring, Haast Bluff, 23
Aug. 1956, G. Chippendale 2578 (BRI, DNA, MEL, NSW, PERTH); Mannanana Range, Petermann
River Reserve, 10 Sep. 1978, T.S. Henshall 2144 (BRI, MEL, NT, PERTH); Elkedra Station; jump
up towards Hatches Creek, 8 Oct. 1979, T.S. Henshall 2747 (CANB, DNA, MEL); Neutral Junction
Station, 7 Apr. 1974, P.K. Latz 5614 (CANB, DNA); Ewalinga Rockhole, E of Docker Creek Settlement,
18 Sep. 1969, J.R. Maconochie 758 (BRI, CANB, DNA, PERTH); NE of Docker River Settlement,
27 Aug. 1973, J.R. Maconochie 1870 (AD, CANB, DNA, MO). WESTERN AUSTRALIA: N of
Kumarina, 1 Nov. 1999, J.A. Chappill & C.F. Wilkins 6321 (PERTH); SW of Warburton Mission, 30
Aug. 1973, N.N. Donner 4493 (AD, PERTH); Little Lofty Ranges, Oct. 1991, H.N. Foote 48 (PERTH);
N of Neale Junction, Gibson Desert, 18 July 1974, A.S. George 11998 (CANB, PERTH); Rudall
River National Park, 17 Aug. 1994, A.E. de Jong s.n. (PERTH); Barlee Range Nature Reserve, SE of
Wongida Well, SSE of Mount Florry, W of Culcra Bore, Barlee Range, 17 Aug. 1994, S. van Leeuwen
1653 (PERTH); S of Kumarina roadhouse, Oct. 1997, M. Ochtman LCS 4119 (PERTH); track along
Rabbit Proof fence, Little Sandy Desert, 14 Aug. 2001, C.F. Wilkins, S. van Leeuwen, K.A. Shepherd,
S. Hopper, P. Nikulinski, B. Bromilow & S. Scourfield 1475 (PERTH).
Distribution. Gompholobium polyzygum occurs in arid inland areas of the Northern Territory and
Western Australia. At the western end of its range it skirts the eastern and south-eastern margins of
the Pilbara bioregion. It may occur in the far-eastern part of this bioregion, but does not overlap the
distribution of G. oreophilum or G. karijini (Figure 6).
Habitat. Gompholobium polyzygum grows in open shrubland or Triodia hummock grassland on lateritic
gravel, red sandy loam, sandstone or skeletal quartzite.
Conservation status. Gompholobium polyzygum is widespread in Western Australia and the Northern
Territory and is not considered to be under threat at this time.
Notes. Gompholobium polyzygum differs from G. karijini and G. oreophilum in having leaves with more
numerous leaflets that are also smaller, more rotund, more crowded and overlapping, and in having
generally broader bracts and bracteoles (0.4–0.8 mm compared to 0.2–0.5 mm wide). In addition, it
differs from G. karijini in being a hairy plant with persistent bracteoles, and from G. oreophilum in
having longer hairs (1–1.3 mm long compared to 0.4–0.8 mm long).
There is significant variation in this species in the areas east of the Pilbara bioregion. This variation
requires detailed study to resolve and is beyond the scope of this paper.
40 Nuytsia Vol. 22 (1) (2012)
Figure 6. Distribution of Gompholobium polyzygum.
Acknowledgements
Western Australia’s Department of Environment and Conservation is acknowledged for financial
assistance received through a Specific Nature Conservation Project grant within the Nature Conservation
Service. Thanks also to Lorraine Cobb (deceased) for the fine illustration and Ian Thompson for his
helpful comments on the manuscript.
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